1. Field of the Invention
The present invention relates to a gas laser oscillator that excites a gas to obtain laser output.
2. Description of the Related Art
A general gas laser oscillator excites a laser gas sealed in a discharge tube by discharge energy between discharge electrodes, and generates laser light having an oscillation wavelength corresponding to the amount of energy emitted when a molecule or atom of the gas in the excited state transits to a lower energy level.
In such a gas laser oscillator, an optimum composition of a laser gas is determined in advance. Then, the pressure of the laser gas in the gas laser oscillator is set to be optimum based on the laser gas having that composition.
When the composition of an optimum laser gas is different from the composition determined in advance and/or the pressure setting of the laser gas in the gas laser oscillator is different from the pressure setting determined in advance, it is not possible to obtain an optimum laser output.
Because of this, in Japanese Unexamined Patent Publication (Kokai) No. 2001-44534, for example, discharge voltage of a laser gas is measured and the composition of the laser gas is adjusted based on the measured discharge voltage. In other words, in Japanese Unexamined Patent Publication (Kokai) No. 2001-44534, the composition of the laser gas is determined from the discharge voltage and the composition of the laser gas is adjusted based on the result.
However, in Japanese Unexamined Patent
Publication (Kokai) No. 2001-44534, it is necessary to generate discharge voltage in order to adjust the composition of the laser gas, and therefore, it is not possible to determine the composition of the laser gas before discharge. In addition, in Japanese Unexamined Patent Publication (Kokai) No. 2001-44534, it is necessary to cause a discharge to occur each time the composition of the laser gas is determined, and therefore, the laser power supply and/or the discharge tube may gradually deteriorate due to the discharge. Further, when the composition of the laser gas is different from the composition determined in advance, an anomalous discharge may occur and the laser power supply and/or the discharge tube may quickly deteriorate.
The present invention has been developed taking the above into consideration, and an object thereof is to provide a gas laser oscillator capable of determining a laser gas without generating a discharge voltage.